1. Field of the Invention
The present invention relates to an image processor for performing multicolor printing by using color ink whose color is different from a process color (spot color ink).
2. Description of the Related Art
In DTP (Desktop Publishing), an image is formed, processed, and edited by a processor such as a personal computer or a workstation, so that a page layout is formed, a film to develop the page layout on a printing plate (CEPS) is formed, and it is directly written on a printing plate, to thereby form a press plate for printing (CTP: Computer to Plate).
When proofreading or the like is carried out before printing using the actual press plate, the page layout displayed on a monitor (comprehensive layout) is printed by a printer such as a page printer, using the WYSIWYG function.
Although four colors (process colors) including cyan, magenta, yellow, and black are used in ordinary color printing, an ink of a color different from a process color (hereinafter, referred to as a “spot color”) may be used depending on necessity. Recently, two-color printing is sometimes used in order to restrain the printing cost. In this case, one process color and one spot color may be used or two spot colors may be used, in order to attain a special effect.
When a simulation of two-color printing is performed in order to obtain the printing image of a comprehensive layout using spot colors, it is difficult to confirm how the actual printed matter will be finished in the case where no printing image other than that using the process colors can be obtained.
Thus, a method has been proposed of printing a color chart with the actual press plate by using the spot colors to be used for the two-color printing, creating a profile for the spot colors (look-up table of CMYK-L*a*b*) by measuring the color chart, and simulating the printing in the spot colors by realizing the CMYK-C′M′Y′K′ conversion using a color management function, with the profile for the spot colors and a profile for a printer (look-up table of L*a*b*-C′M′Y′K′)(for example, refer to Japanese Patent Application Laid-Open No. 2000-62253).
Japanese Patent Application No. 2003-71484 provides a method of supplying a color comprehensive layout with each color replaced with each desired ink color (spot color) in a document prepared, for example, in two colors of C, M, Y, and K.
However, when image data for two-color printing is prepared using spot colors, the name of the spot color (type of the spot color) and the ratio of the spot colors have to be considered. However, since there are thousands of spot colors, it is difficult to ascertain each coloring depending on the combinations of only the spot colors and the combinations of a spot color and a process color. Accordingly, there arises a problem in that the same coloring as used in the past cannot be reproduced even when there is a request for the same coloring.